Fusing of fans to comply with manufacturers recommended instructions

[garaoke]

Manufacturers want there fans fused to 3a on the permanent feed but the switch wire is still on the 6a MCB doing an eicr is a c2 if there is no RCD protection

 

[Toneyz]

I assume you mean as it in a bathroom or because the cable is buried in the wall? C3 for both if to a previous edition of the regs ie full supplementary bonding was in place if not C2.

 

[mattg4321]

If manufacturers want a 3a fuse, why don't they bloody well fit one inside the fan. Bloody irritating this!

 

[Toneyz]

If manufacturers want a 3a fuse, why don't they bloody well fit one inside the fan. Bloody irritating this!

A lot of lighting manufacturers do exactly that.

 

[Deleted member 9648]

Manufacturers want there fans fused to 3a on the permanent feed but the switch wire is still on the 6a MCB doing an eicr is a c2 if there is no RCD protection

IMO if there is a 3a fuse on the permanent line then it complies with manufacturers instruction. The switched live is only a trigger, the fan uses the permanent line to operate so a fuse on that line will serve the purpose intended.

 

[garaoke]

I assume you mean as it in a bathroom or because the cable is buried in the wall? C3 for both if to a previous edition of the regs ie full supplementary bonding was in place if not C2.

 

[garaoke]

IMO if there is a 3a fuse on the permanent line then it complies with manufacturers instruction. The switched live is only a trigger, the fan uses the permanent line to operate so a fuse on that line will serve the purpose intended.

Switch left on is a supply to the timer at a higher rating than the feed

 

[Deleted member 9648]

Switch left on is a supply to the timer at a higher rating than the feed

The motor runs on the permanent line though, it wont run at all just on the switch line.

 

[garaoke]

If manufacturers want 3a protection they should provide it

 

[leebut]

Why not just wire the bathroom with a 3 amp fuse to the lighting and fan then wire everything downstream off the fused spur, problem solved

 

[Richard Burns]

The manufacturers want both permanent and switch line fused by a single fuse and since this involves the wiring outside the fan they cannot install a fuse in the fan.
If they only wanted the permanent line fused they could do this, but do not because that is not their intention.
From a fusing point of view the fuse is there to prevent cables being overloaded and causing fire.
From a protective point of view the fuse should disconnect the power to a piece of equipment.
Fusing the permanent line only will do the former but not the latter.
Someone removing the fuse or finding the fuse had blown might work on the fan not realising there was still a live supply to the fan (if the switch was on), though they should check for dead at the equipment and not just at the supply.
For coding this is down to the inspector, the lack of RCD protection would be a situation where in case of a fault it could give rise to danger, the lack of a 3A fuse on the switched line would be a far lower risk and almost minimal if a 3P isolator were fitted, so the coding would apply to the lack of RCD protection.

 

[Taylortwocities]

I’m sure this has been said before but
I’ll do it again…

A 3amp fuse on a (usually lighting) circuit that is protected by a 6amp MCB is pointless. The MCB will trip a long time before a 3A fuse will pop.

I’ve a feeling the 3A thing originally came from when the fan may be powered from something like a ring final which has a much higher current rating.

 

[leebut]

A lot of electricians forget that the wiring regulations stipulate that a manufacturers instructions supersedes the wiring regulations, so if a manufacturer states they require a 3 amp fuse on that product you have to install a fuse on the circuit like I mentioned previously the best way to cover this point is to install a 3amp fused spur at the loop then everything from that point onwards is protected by that fuse on both permanent and switched conductors, the idea of the 3amp fuse is to cover every eventuality on an installation from a BS 3036 fuse through to BS60898 MCB or BS61009 RCBO, I agree the MCB/RCBO would trip quicker than the fuse but at least the installation would comply with the manufacturers instructions.

 

[Deleted member 9648]

I’m sure this has been said before but
I’ll do it again…

A 3amp fuse on a (usually lighting) circuit that is protected by a 6amp MCB is pointless. The MCB will trip a long time before a 3A fuse will pop.

I’ve a feeling the 3A thing originally came from when the fan may be powered from something like a ring final which has a much higher current rating.

Some time back there was an instance of one of these fans causing a fire, presumably it seized. It ended up in court and the manufacturers gettout was that a 3a fuse had not been fitted as per instructions. This despite the fact that we all know a 3a fuse would make no difference.

 

[leebut]

Some time back there was an instance of one of these fans causing a fire, presumably it seized. It ended up in court and the manufacturers gettout was that a 3a fuse had not been fitted as per instructions. This despite the fact that we all know a 3a fuse would make no difference.

Completely agree I remember reading the same article in one of the trade magazines, the blame was put back onto the installer